In recent years, plastic materials including engineering plastics have been widely used as an alternative to metal materials or inorganic materials such as glass by taking advantage of their toughness, processability, etc. However, they must be provided with surface protecting layers due to their inferior surface hardness and scuffing resistance.
According to conventional techniques for making the surfaces of plastics hard, heat-curing resins such as those based on organosiloxane and melamine or polyfunctional polyacrylic photosetting resins have been coated on them, or thin metal films have been formed on them by vacuum deposition, sputtering or other means.
A problem with conventional scuffing-resistant surface protecting layers obtained with heat-curing or photosetting resins, however, is that they are so lacking in flexing properties that they are likely to crack. Thus, when forming surface protecting layers on curved moldings or synthetic resin films, they are still far from satisfactory, since some difficulty is involved in processing them into curved shapes or they crack by flexing. Even when used as surface protecting layers for flat planes, they are disadvantageous in that once injured, they are never restored to the original state or remain seriously damaged. Problems with surface protecting layers formed of thin metal films, on the other hand, are that because of being processed in vacuo, they are of low productivity and have difficulty in being processed into large sizes.